///they are harder than a deadlift (technique-wise)...
Olympic Lift
Olympic Movement produces some, if not, the highest Power Output in sports. (Research Dr John Garhammer)
Bill Starr's book,
The Strongest Shall Survive, from the 1970's determined that Football Player should center their training around Squats, Bench Presses, Deadlifts and Power Cleans. That model continues to the one that is implemented with Strength Coaches.
The foundation of Mark Rippetoe's Starting Strength is founded on this principle; which is understandable. Rippetoe is a disciple and was a close friend of Starr, who pass away.
Olympic Lift Technique
As Ryan states, Olympic Lifts require more technique. More time is required in learning them. While learning them on your own is possible, as with most thing, good coaching makes a huge difference.
It's hard for someone to evaluate their technique, if they are unfamiliar with the nuances of the movement.
The problem with posting information online is that you get conflicting feed back; a lot is incorrect. Due a lack of knowledge, it hard to know who to believe; who's right and wrong.
Suggested Solutions
1) Self Learning
This video series by Harvey Newton is one of the best at breaking down how to perform Olympic Movements.
2) The Clean High Pull
Increase muscular power and overall athleticism with this challenging, yet fun, lift.
www.t-nation.com
Allen Hedrick is one of the best Strength Coaches in the game.
For those interested in developing Power with an Olympic Movement, this method is one of the best.
While some technique is necessary, it is one of the easier to learn.
Video Demonstration
3) Heavy Kettlebells Swings
Research (Dr Bret Contreras) has demonstrated Heavy Kettlebell Swings produce Power Output that rivals Olympic Movements. A good rule thumb, as previously posted, is to perform Kettlebell swings with approximately one-third of your body weight and higher.
a) The learning curve on Kettlebell Swing is much faster
b) Power development is approximately the same as Olympic Movements.
4) Trap Bar Jump Squats
Research shows that Trap Bar Jumps rival the Power Output of Olympic Pulls, which makes sense. Essentially, Trap Bar Jumps is a what you might term as a Low Olympic High Pull. The Trap Bar Jump ending with a Shrug, around in he waist area. An Olympic High Pull, dependent on the load, can be in the chest area.
...if you do deadlifts and kettlebell swings I doubt you’re really missing anything..
Vertical and Horizontal Power
Overall, for most, I agree; you're not going to miss much of anything.
However, for High Jumpers in Track and Basketball Players, Vertical Power Movements would be more specific to their Sport: Olympic High Pulls and Trap Bar Jumps.
For Long Jumpers in Track, a Vertical Power Movement like Kettlebell Swing would be more sports specific.